EXCELLENT INSULATING AND CORROSION RESISTANT PERMANENT MAGNET AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To make feasible of the formation of the films having excellent bond properties, insulating and corrosion resistance on the surface of an R-Fe-B base permanent magnet body by a method wherein film made of a Si-Na-O base glass material and fine chrystalline material in a specific thickness is formed on the surface of an R-Fe-B base permanent magnet body made of tetragonal main phase. SOLUTION: The permanent magnet is provided with film layers made of Si-Na-O base glass material and fine chrystalline material having excellent insulating properties and corrosion resistance as well as high magnetic properties on the surface of an R-Fe-B base permanent magnet body. In order to manufacture this permanent magnet, firstly, the surface of the R-Fe-B base permanent magnet body made of cleaned up tetragonal main phase is coated with soda silicate base water glass to be sprayed in immersion process so that the water glass may be heated and dried up in an inert gas at 50-350 deg.C for 10-600min. to form film layers made of a 1 to 30μm thick Si-Na-O base glass material and a fine chrystalline material. Furthermore, either oxide particles or metallic particles may be added to the water glass for the stabilization of the film layers.